Electrically driven equipment



March 29, 1966 C, H, G UBBINS 3,242,998

ELECTRICALLY DRIVEN EQUIPMENT Filed May 2I5, 1963 United States Patent O3,242,998 ELECTRICALLY DRIVEN EQUIPMENT Charles Henry Gubbins, London,England, assignor .to

Wolf Electric Tools Limited, London, England, a British company FiledMay 23, 1963, Ser. No. 282,802 Claims priority, application GreatBritain, May 28, 1962, 20,446/ 62 2 Claims. (Cl. 173-163) Tlhisinvention relates to electrically powered apparatus from which the poweroutput is taken by Way of a rotating spindle connected at one end to thedrive, and designed for connection to the member to be driven (Le. theworking member) |at its other end. Examples of such apparatus `areelectric d-rills, in which the member to he driven is the chuck, androtary poli-shers.

According to the present invention electrically powered apparatusincluding an electric motor connected to drive a rotatable spindlehaving means tor iixing a Working member to it has a casing ofinsulating material, and the spindle is also formed of insulatingmaterial. It will be seen .that in this apparatus all the exposed partsare fully insulated even though a rotary output is taken from theapparatus. To insulate previous equipment ot this type it has beennecessary to make 'a number off separate insulated connections withinthe equipment, and even with these connections it has proved difficultto effect adequate insulation where the rot-ary output is led throughthe leasing of the apparatus. Apparatus according to the invention doesnot need internal insulating connections, and the method of insulationis much simpler. Furthermore apparatus insulated in this way is saferthan that insulated internally `since the problem ci" electivelyinsulating the rotary spindle is solved much more satisfactorily.

`For low torque applications it has been found that the Working memfbercan be xed directly to the spindle, but preferably the spindle has ametal insert moulded in `situ .in the insulating material, the inserthaving la threaded part for receiving a similarly threaded part as themember. This enables production of the spindle to be effected verycheaply and easily, and allows a good drive transmission from thespindle to the working member.

Examples of apparatus according to the invention will now be describedin more detail with .reference to the accompanying drawings in which:

FIGURE 1 is a .pant section part side elevation through part of one formof apparatus;

FIGURE 2 is a section on the line II--I I of FIGURE 1;

FIGURE 3 is ya section of part of a second form ot the apparatus;

'FIGURE 4 is a section on the line IV-IV of FIG- URE 3; and

FIGURE 5 is .a part-section through an alternative form of spindle.

FIGURE 1 shows one end of the casing 1 of an electrically poweredapparatus driven 'by an electric motor (not shown) by way ot a pinion 2on the output shaft of the motor. The pinion meshes with a gear wheel 3whi-ch is litted over the end 4 of a `spindle shown generally as 5. Theend 4 i-s ot nonecircular cross-section so that the .gear wheel andspindle are held to rotate together. The gear Wheel is -held in positionaxially on the spindle by a spring clip 6 of the non-return type whichcan be forced onto the end of the spindle into contact with the gearWheel, but has pants engaging the spindle to prevent the clip beingIremoved. This spring clip bears [against Ione side of the gear Wheel,and the other side ot the gear Wheel bears against the inner race oft \abearing 7. This bearing -7 to- 3,242,998 Patented Mar. 29, 1966 getherwith a further bearing 8 mount lt-he spindle for rotation within thecasing 1. The end of the spindle removed from the gear wheel has laninternally tapped metal insert 16 positioned in it for receiving aWorking member. For example if the apparatus is 1an electric drill thisinsert would receive the threaded bos-s ot the chuck. In otherappplications it could receive threaded bosses on the en'ds of suchthings as polishing pads, sanding pads or in tact any working memberneeding a rotary drive.

'Ilhe casing 1 o-f the apparatus is made trom insulating material, andthe spindle is also formed from insulating material, a suitable materialfor the spindle being glass lilled nylon. Both the casing and thespindle are moulded, -and in the case ott the spindle the metal insert16 is moulded in situ.

In the alternative construction shown in FIGURES 3 and 4 the apparatusis similar and parts identical to those of the apparatus of FIGURE lIare denoted by the sameY reference number. This apparatus differs inthe mode oi attachment of the gear Wheel 3 to the spindle 5, `and inthis case Ithe end yott the spindle that receives the gear Wheel issplined as shown at 10 and lthe gear wheel fitted onto the splines. Inthis case the gear wheel is held axially against the inner race of thebearing '7 by a plate 11 which is held against a shoulder 12 formedround the inner surface of the pinion by a screw 13 received in aninternally tapped metal insert 14 in the end of the spindle. The metalinsert 16 at the other end of the spindle is the same as that shown inFIGURE l, but in fact this insert may be ot any suitable iorm forreceiving the required working member.

Once again both the casing and the spindle yare moulded trom insulatingmaterial, and in this case both Ametal inserts 14 and 16 are moulded insitu in the material of the spindle.

The spindle shown in either of these figures may be replaced lby thatshown in FIGURE 5 if desired. This dilens in that it has an externallythreaded boss `1'7 projecting from the insert rather than the tappedbore within the insert.

lIt will be seen from the drawings that all the exposed parts except themetal inserts 16 are of insulating material, `and even the metal insert16 is embedded in insulating material `and cannot be in any electricalcontact with .any internal part of the apparatus. This yarrangementmeans that all the exposed parts are fully insulated.

I claim:

1. In .combination with an electric motor driven power tool having 'aninsulating housing, mechanical power output ymeans comprising a spindleformed of insulating material and having a blind bore at the outer endthereof, said spindle being rotatably mounted in and enclosed by saidinsulating housing to be driven by said motor, and having means withinsaid blind bore lfor attaching a working to'ol thereto.

2. The combination as defined by claim 1 which further includes a gearrigidly attached to said spindle at its innermost end for engaging amating gear driven by said motor.

References Cited by the Examiner UNITED STATES PATENTS 1,189,184 6/1916Whiteside 310-43 1,960,470 5/ 1934 Whiteside S10-43 2,237,999 4/1941Newman 310-50 3,121,813 2/1964 Pratt et al. 310--50 WILLIAM W. DYER,IR., Primary Examiner. FRANCIS S. HUSAR, Examiner.

1. IN COMBINATION WITH AN ELECTRIC MOTOR DRIVEN POWER TOOL HAVING ANINSULATING HOUSING, MECHANICAL POWER OUTPUT MEANS COMPRISING A SPINDLEFORMED OF INSULATING MATERIAL AND HAVING A BLIND BORE AT THE OUTER ENDTHEREOF, SAID SPINDLE BEING ROTATABLY MOUNTED IN AND CLOSED BY SAIDINSULATING HOUSING TO BE DRIVEN BY SAID MOTOR, AND HAVING MEANS WITHINSAID BLIND BORE FOR ATTACHING A WORKING TOOL THERETO.